The proposed research program will investigate the effects of ethanol administration on the major varieties of social aggression in rodents. These will include agonistic interactions of dominant and subordinate animals in established groups or during the formation of dominance hierarchies, attack on territorial intruders, female attack on males as a function of parturitional status, and fear-based attack by both male and female rats. These results will clarify the effects of ethanol on the two major aggression patterns in animals which serve as the precursors of human angry and fearful aggression. The second series of studies will examine the mechanisms of alcohol potentiation of aggression. Direct effects, effects through disinhibition by fear, and effects which interact with subject characteristics will be evaluated by analysis of ethanol effects in relation to known motivational and emotional characteristics of different classes of subjects. Finally, the program will attempt to evaluate the effects of high-level social stressors upon voluntary ethanol ingestion in established colonies in ecologically valid settings. This will also include analyses of subsequent social behaviors of the voluntarily ingesting subjects, to provide an integrated analysis of the interaction of social stress and alcohol in a model which has previously proved successful in extensions to human aggressive behaviors.